The McDonnell Douglas MD-80 series are twin-engine, medium-range, single-aisle commercial jet airliners. The MD-80 aircraft were lengthened and updated from the DC-9. The MD-80 series can seat from 130 up to 172 passengers depending on variant and seating arrangement.

The MD-80 series was introduced commercially in October 1980 by Swissair. The MD-80 series was followed into service in modified form by the MD-90 in 1995 and the MD-95/Boeing 717 in 1999.

Design and development

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Background

Douglas Aircraft developed the DC-9 in the 1960s as a short-range companion to their larger DC-8.[1] The DC-9 was an all-new design, using two rear fuselage-mounted turbofan engines, and a T-tail. The DC-9 has a narrow-body fuselage design with 5-abreast seating, and holds 80 to 135 passengers depending on seating arrangement and aircraft version.

The MD-80 series was the second generation of the DC-9. It was originally called the DC-9-80 series and the DC-9 Super 80[2] and entered service in 1980. The MD-80 series was then developed into the MD-90 entering service in 1995. The last variant of the family was the MD-95, which was renamed the Boeing 717-200 after McDonnell Douglas's merger with Boeing in 1997.

The DC-9 family is one of the most successful jet airliners with a total of over 2,400 units produced; it ranks third behind the second place Airbus A320 family with over 4,000 produced, and the first place Boeing 737 with over 6,000 produced.

MD-80 series

The MD-80 series is a mid-size, medium-range airliner that was introduced in 1980. The design was the second generation of the DC-9 with two rear fuselage-mounted turbofan engines, small, highly efficient wings, and a T-tail. The aircraft has distinctive 5-abreast seating in coach class. It was a lengthened DC-9-50 with a higher maximum take-off weight (MTOW) and a higher fuel capacity. The aircraft series was designed for frequent, short-haul flights for 130 to 172 passengers depending on plane version and seating arrangement.

The development of MD-80 series began in the 1970s as a growth version of the DC-9 Series 50. Availability of new Pratt & Whitney JT8D higher bypass engines drove early studies including designs known as Series 55, Series 50 (Re-fanned Super Stretch), and Series 60. The design effort focused on the Series 55 in August 1977. With the projected entry into service in 1980, the design was marketed as the "DC-9 Series 80". Swissair launched the Series 80 in October 1977 with an order for 15 plus an option for five.[1]

The Series 80 featured a fuselage 14 feet 3 in (4.34 m) longer than the DC-9-50. The DC-9 wings were redesigned by adding sections at the wing root and tip for a 28% larger wing. The initial Series 80 first flew October 19, 1979.[1]

It entered service in 1980. Originally it was certified as a version of the DC-9, but was changed to MD-80 in July 1983, as a marketing move. New versions of the series were initially the MD-81/82/83 and the shortened MD-87, even though their formal certification was DC-9-81/82 etc. Only the MD-88 was given an "MD" certification, as was the later MD-90.

The MD-80 versions have cockpit, avionics and aerodynamic upgrades along with the more powerful, more efficient and quieter JT8D-200 series engines, which are a significant upgrade over the smaller JT8D-15, -17, -11, and -9 series. The MD-80 series aircraft also have longer fuselages than their earlier DC-9 counterparts, as well as longer range. The MD-80's production ended in 1999. Notably, customers such as American Airlines still refer to the planes in fleet documentation as "Super 80". This model is still flown extensively by American Airlines and Delta Air Lines. Comparable airliners to the MD-80 series include the Boeing 737 and Airbus A320.

Derivative designs

The MD-90 was developed from the MD-80 series and was a 5 feet longer, updated version of the MD-88 with a similar electronic flight instrument system (EFIS) (glass cockpit), and improved, and quieter IAE V2500 engines. The MD-90 program was launched in 1989, first flew in 1993 and entered service in 1995.

A number of other variants were proposed that never saw production. One proposal was the MD-94X which was fitted with an unducted fan engine. The MD-81 was used as a testbed for unducted fan engines, such as the GE 36 and the Pratt and Whitney/Allison 578-DX.[3]

The MD-95 was developed to replace early DC-9 models, then approaching 30 years old. The project completely overhauled the original DC-9 and reinvented it for modern transport. The aircraft is slightly longer than the DC-9-30 and is powered by new Rolls-Royce BR715 engines. The MD-95 was renamed Boeing 717 after the McDonnell Douglas—Boeing merger in 1997.

Due to the usage of the aging JT8D engine, the MD-80 is not fuel efficient compared to the A320 or newer 737 models; it burns 1,050 gallons of jet fuel per hour on a typical flight, while the larger Boeing 737-800 burns only 850 gallons per hour (19% reduction). Many airlines have started to retire the type in the 2000s. Alaska Airlines' tipping point in using the 737-800 was the $4 per gallon price of jet fuel the airline was paying by the summer of 2008; the airline stated that a typical Los Angeles-Seattle flight would cost $2,000 less, using a Boeing 737-800, than the same flight using an MD-80. American Airlines has announced plans to retire at least 20 MD-80s,[5] and has accelerated delivery of new 737-800s,[6] while Midwest Airlines announced on July 14, 2008, that it would retire all 12 of its MD-80s (used primarily on routes to the west coast) by the fall.[7][8] The JT8D's comparatively lower maintenance costs due to simpler design help narrow the fuel cost gap.[9]

Variants

MD-81 (DC-9-81)

Originally the Super 81, basic production variant with two 18,500 lb thrust JT8D-209 engines.

MD-82 (DC-9-82)

Originally the Super 82, variant for hot and high operations with 20,000 lb thrust JT8D-217 engines and increased maximum take off weight.

On December 27, 1991, SAS Flight 751, an MD-81, OY-KHO "Dana Viking" crash landed at Gottröra, Sweden. In the initial climb both engines ingested ice broken loose from the wings (which had not been properly de-iced before departure). The ice damaged the compressor blades causing compressor stall. The stall further caused repeated engine surges that finally destroyed both engines, leaving the aircraft with no propulsion. The aircraft landed in a snowy field and broke in three parts. No fire occurred and all aboard survived.

On June 1, 1999, American Airlines Flight 1420, an MD-82 attempting to land in severe weather conditions at Little Rock Airport overshot the runway and crashed into the banks of the Arkansas River. Eleven people, including the captain, died.

On January 31, 2000, Alaska Airlines Flight 261, an MD-83, crashed in the Pacific Ocean, due to loss of horizontal stabilizer control.[15] All 88 people on board were killed. Following the crash, the acme nut and jackscrew recovered from the aircraft were found to be excessively worn[16] and found to be the cause of the crash due to inadequate maintenance. The FAA ordered airlines to inspect and lubricate the jackscrew more frequently.[17]

On October 8, 2001, Scandinavian Airlines Flight 686, an MD-87 (SE-DMA) collided with a small Cessna jet during take-off at Linate Airport, Milan, Italy. The Linate Airport disaster left 118 people dead. The cause of the accident was a misunderstanding between air traffic controllers and the Cessna jet, and the SAS crew had no role in causing the accident. Also the ground movement radar was inoperative at the time of the accident.

On March 4, 2006, Lion Air Flight 8987, an MD-82, after landing at Juanda International Airport reverse thrust was used although stated to be out of order, this caused the aircraft to veer to the right and skid off the runway coming to rest 7,000 ft from the approach end of RWY10. No one was killed but the aircraft was damaged with a repair bill of $3 million.[19]

Between March 26, and March 27 then again between April 8, and April 12, 2008 an FAA safety audit of American Airlines forced the airline to ground its entire 300 MD-80 series fleet, to inspect the aircraft's hydraulic wiring. American was forced to cancel nearly 2500 flights in March and over 3200 in April.[23] In addition, Delta Air Lines inspected its own MD-80 fleet to ensure its 117 MD-80s were also operating within regulation. This prompted Delta to cancel 275 flights.[24]

On August 20, 2008, Spanair Flight 5022, an MD-82 registration EC-HFP from Madrid's Barajas Airport crashed shortly after takeoff on a flight to Las Palmas de Gran Canaria in the Canary Islands. The MD-82 had 162 passengers and ten crew on board, of whom 18 survived. The crash was caused by an attempt to take off with the flaps and slats retracted. The flight crew omitted the "set flaps and slats" item in both the After Start checklist and the Takeoff Imminent checklist.[25]